feat: service console auto-connect, settings panel, and batch of enhancements

- Auto-connect WebSocket on page load in service console
- Settings modal for editing sgclaw_config.json (API key, base URL, model, skills dir, etc.)
- UpdateConfig/ConfigUpdated protocol messages for remote config save
- save_to_path() for SgClawSettings serialization
- ConfigUpdated handler in sg_claw_client binary
- Protocol serialization tests for new message types
- HTML test assertions for auto-connect and settings UI
- Additional pending changes: deterministic submit, org units, lineloss xlsx export, browser script tool, and docs

🤖 Generated with [Qoder][https://qoder.com]

src/bin/sg_claw_client.rs

@@ -84,6 +84,13 @@ fn run() -> Result<(), String> {
                             break;
                         }
                         ServiceMessage::Pong => {}
+                        ServiceMessage::ConfigUpdated { success, message } => {
+                            if success {
+                                println!("config updated: {message}");
+                            } else {
+                                eprintln!("config update failed: {message}");
+                            }
+                        }
                     }
                 }
                 Message::Close(_) => {